Setting Job-Shop Due-Dates with Service-Level Constraints

Abstract

The job-shop due-date assignment problem arises when a manager needs to ‘promise’ a delivery date to a customer. Previous methods yield due-dates which are either optimistic (unlikely to be achieved) or conservative (the promise will be met, but too easily, because the date given was very pessimistic). This paper investigates the due-date assignment problem with a customer ‘service-level’ constraint, the percentage of time that promised delivery dates are honoured. We formulate a rule to attain this service level, yet maintain as short a due-date lead time as possible. Unlike previous attempts, this due-date rule considers not only the job content and instantaneous shop congestion information, but also implicitly incorporates information on how the jobs will be scheduled (or ‘loaded’) once they are in the shop. We simulate a single-machine shop for various measures of performance under several dispatching priorities, comparing our due-date rule with one reported to yield satisfactory performance. Our rule meets all requirements and is found to be superior for most measures of performance.

Keywords:

• due-dates
• job-shop
• scheduling